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MathGroup Archive 2000

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Re: Simple equation checking..

  • To: mathgroup at smc.vnet.net
  • Subject: [mg25664] Re: [mg25625] Simple equation checking..
  • From: "Matt Herman" <Henayni at hotmail.com>
  • Date: Wed, 18 Oct 2000 02:52:33 -0400 (EDT)
  • References: <200010160704.DAA06874@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Ian,

Mathematica can do all of these.
In[14]:=
(E^(I r)//ExpToTrig)/.r->\[Pi]

Out[14]:=
-1

I don't believe you got the derivative right.
If you want to check, do D[f,x]-(whatyoudidbyhand)//FullSimplify.
If they are equal, you'll get 0.

Matt

----- Original Message -----
From: "Ian Fan" <ian at v-wave.com>
To: mathgroup at smc.vnet.net
Subject: [mg25664] [mg25625] Simple equation checking..


>
> Hi again, thanks for all the help with my last question but now I am stuck
> with another problem if anyone would be so kind enough to help.
>
> I am looking for a way to check equations, for example, the derivative of
> ((x^3 - 4x + 3)/x^(4/3) is (5x^(10/3) - 8x^(7/3) - 12x^(1/3))/(3x^(8/3))
> when calculated via hand but is (3x^2 - 4)/x^(4/3) - 4(x^3 - 4x +
> 3)/(3x^(7/3)) when put through mathematica. What I would like to do is if
> there is any way to equate the two and see if the statement is true
because
> obviously it can look like two completely different answers (to a student)
> when they are in fact the same.
>
> Another example would be, is there any way to check if E^(:ii:Pi) = -1 was
> true (at least according to the Euler-Moivre equation), using Mathematica?
>
> I tried using the "Check" command but I don't know what two arguments
there
> are (I tried putting in lhs,rhs but I just got the former as an output).
>
> Thanks in advance,
> Ian Fan
>
>
>
>


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